1. Field of the Invention
This invention pertains to the field of optical measuring and testing, more particularly to the measurement of angles in two planes to determine the two dimensional slope of a wave surface.
2. Description of the Prior Art
It is known to detect the presence or passage of a wave or wave on a surface by apparatus detecting a change in the angle of a beam reflected from the surface or a change in the gross reflectance of the surface.
However, it is often desirable to distinguish a direct reflection or emission from an object from a simultaneously received indirect reflection via a time changing wave surface. If the time changing surface can be mathematically characterized, the direct transmission can be distinguished from the indirect reflection from the wave surface.